It is known that red phosphorus is an excellent flame-retardant for many types of polymeric substances.
It is known too that, in order that the flame-retarding effect of red phosphorus may have--as is desired--a high efficiency, it is necessary that red phosphorus should be added by distributing it in the mass of said polymeric substances in a homogeneously, finely particulated form. This cannot be accomplished without technical difficulties according to the usual methods which, besides, having some drawback connected with the safety and environmental hygiene in relation to the necessity of handling fine red phosphorus powders which, as is known, are toxic (formation of phosphine by reaction with hydrogen-containing substances, in particular water) and create combustion hazards.